AB1549 VALUE OF ULTRASOUND FOR THE EARLY DETECTION OF INFLAMMATORY ABDOMINAL AORTIC ANEURYSMS
Authors: B. Slijkhuis, S. Konter, D. Liesker, A. Possel-Nicolai, E. Brouwer, R. Slart, A. Van Roon, B. Saleem, D. J. Mulder
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Inflammatory abdominal aortic aneurysm (iAAA), a form of chronic periaortitis, is a frequently overlooked disease, occurring in patients with abdominal aneurysms (AAA). iAAA is strongly associated with underlying systemic inflammatory diseases such as IgG4-related disease (IgG4-RD),<sup>[1]</sup> potentially leading to retroperitoneal fibrosis (RPF). Ultrasound (US) is a widely available and low-cost imaging tool that may allow the detection of iAAA at an early-stage prior development of severe complications in patients with AAA. <h3>Objectives</h3> This study aims to assess the feasibility of using US to detect iAAA in a small case series (exploratory cohort). And to structurally assess the diagnostic potential and overall incidence of iAAA using US in a larger retrospective cohort of patients in follow-up for AAA (validation cohort). <h3>Methods</h3> In the exploratory cohort, thirteen patients (median age 64 (61;72) years; 100 % male) with an established diagnosis of iAAA of whom US and CT findings were available were retrospectively included. The diagnosis of iAAA was based on a typical cuff surrounding the aneurysm on CT. Other potential causes such as infections and malignancies were ruled out by microbiological studies and when indicated by histology and/or FDG-PET scanning. Secondly, the validation cohort consisted of 191 patients (median age 74 (67;80) years; 73.3 % male) diagnosed with AAA who were in US follow-up for AAA without prior surgical intervention. In patients in whom a CT was (n=157) the diagnostic potential of US was explored using CT imaging as the golden standard. Perianeurysmal inflammation was assessed on US, as illustrated in Figure 1A, using a Siemens Acuson with 6 Mhz convex transducer in B-mode. In the validation cohort, US images were assessed by two independent observers blinded for the diagnosis. <h3>Results</h3> In the exploratory cohort, 62% were smokers, 77% had hypertension, 31% and were diagnosed with IgG4-RD. CRP and BSE levels were 54.5 (±66.2) mg/L and 59.8 (±51,1) mm/h. All patients showed a typical hypoechogenic cuff surrounding the aortic wall eccentric to the calcified medial layer of the aneurysm, see figure 1B). The median anteroposterior diameter of the aneurysm itself was 5.7 cm (4.8; 6.1) and 0.64 cm (0.49; 0.84) of the cuff. In the validation cohort, 180 of 191 (94.2%) patients with AAA showed no evident signs of a hypoechogenic cuff on ultrasound. Of the remaining 11 patients, 8 (4.2%) showed the cuff surrounding the aortic wall and were identified as having iAAA. In 3 (1.6%) an iAAA could not be ruled out based on US. In 149 patients with both a negative US and available CT, all CT scans were negative as well. In the 8 patients with an evident cuff on US, the median age was 66 (65;79) years; and 100% were male, definite IgG4-RD was present in 25% (n=2) of the cases. This amounts to a sensitivity of 100% and a specificity of 98%. <h3>Conclusion</h3> This retrospective study indicates that iAAA can be identified with US as a hypoechogenic cuff surrounding the aortic wall of the aneurysm. US could be used to rule out iAAA safely. However, in inconclusive cases, additional CT imaging is warranted. Besides a possible cost and radiation dose reduction, using US may facilitate earlier recognition and treatment of iAAA and underlying systemic inflammatory diseases such as IgG4-RD. Although this is the first study to structurally investigate US in iAAA, our results need validation in a prospective study. <h3>Reference</h3> [1]Kasashima F, Kawakami K, Matsumoto Y, Endo M, Kasashima S, Kawashima A. IgG4-Related Arterial Disease. <i>Ann Vasc Dis</i>. Published online 2018. doi:10.3400/AVD.RA.18-00012 <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> Berend Slijkhuis: None declared, Sherilyn Konter: None declared, David Liesker: None declared, Annet Possel-Nicolai: None declared, Elisabeth Brouwer Speakers bureau: Dr. E. Brouwer as an employee of the UMCG received speaker fees and consulting fees from Roche in 2017, 2018 which were paid to the UMCG., Riemer Slart Grant/research support from: Prof. dr. Slart received unrestricted research grants from Siemens Healthineers and Pfizer, Arie Van Roon: None declared, Ben Saleem: None declared, Douwe J Mulder Grant/research support from: Dr. DJ Mulder as an employee of the UMCG received research grants from Sanofi which were paid to the UMCG.